* @brief Feature Salient part of an image. Please refer * to the Appendix of "A Multi-State Constraint Kalman * Filter for Vision-aided Inerti

* @brief IMUState_aug Augmented state for IMU, including only orientation and position */

Measurement for one features

* @brief IMUState State for IMU */

* @brief ImageProcessor Detects and tracks features * in image sequences. */

Measurements for features in one camera img

* @brief Manager of the system. */